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排序方式: 共有497条查询结果,搜索用时 15 毫秒
411.
Broderick P Carvajal-Carmona L Pittman AM Webb E Howarth K Rowan A Lubbe S Spain S Sullivan K Fielding S Jaeger E Vijayakrishnan J Kemp Z Gorman M Chandler I Papaemmanuil E Penegar S Wood W Sellick G Qureshi M Teixeira A Domingo E Barclay E Martin L Sieber O;CORGI Consortium Kerr D Gray R Peto J Cazier JB Tomlinson I Houlston RS 《Nature genetics》2007,39(11):1315-1317
To identify risk variants for colorectal cancer (CRC), we conducted a genome-wide association study, genotyping 550,163 tag SNPs in 940 individuals with familial colorectal tumor (627 CRC, 313 advanced adenomas) and 965 controls. We evaluated selected SNPs in three replication sample sets (7,473 cases, 5,984 controls) and identified three SNPs in SMAD7 (involved in TGF-beta and Wnt signaling) associated with CRC. Across the four sample sets, the association between rs4939827 and CRC was highly statistically significant (P(trend) = 1.0 x 10(-12)). 相似文献
412.
413.
Ko H Takei K Kapadia R Chuang S Fang H Leu PW Ganapathi K Plis E Kim HS Chen SY Madsen M Ford AC Chueh YL Krishna S Salahuddin S Javey A 《Nature》2010,468(7321):286-289
Over the past several years, the inherent scaling limitations of silicon (Si) electron devices have fuelled the exploration of alternative semiconductors, with high carrier mobility, to further enhance device performance. In particular, compound semiconductors heterogeneously integrated on Si substrates have been actively studied: such devices combine the high mobility of III-V semiconductors and the well established, low-cost processing of Si technology. This integration, however, presents significant challenges. Conventionally, heteroepitaxial growth of complex multilayers on Si has been explored-but besides complexity, high defect densities and junction leakage currents present limitations in this approach. Motivated by this challenge, here we use an epitaxial transfer method for the integration of ultrathin layers of single-crystal InAs on Si/SiO(2) substrates. As a parallel with silicon-on-insulator (SOI) technology, we use 'XOI' to represent our compound semiconductor-on-insulator platform. Through experiments and simulation, the electrical properties of InAs XOI transistors are explored, elucidating the critical role of quantum confinement in the transport properties of ultrathin XOI layers. Importantly, a high-quality InAs/dielectric interface is obtained by the use of a novel thermally grown interfacial InAsO(x) layer (~1?nm thick). The fabricated field-effect transistors exhibit a peak transconductance of ~1.6?mS?μm(-1) at a drain-source voltage of 0.5?V, with an on/off current ratio of greater than 10,000. 相似文献
414.
高海健;陈务军;付功义 《华南理工大学学报(自然科学版)》2010,38(7)
薄膜结构模态特性是研究其动力性能的基础,本文首先根据柔性薄膜结构受力特点,考虑大变形、初始预应力刚化几何非线性效应,通过小杨氏模量法找形分析得到平衡形态,继承其位形与初始平衡应力,然后采用分块兰索斯法对薄膜充气梁模态进行数值计算分析,考察了影响薄膜充气梁模态特性的主要因素:压力、薄膜厚度、管径(长细比)。提出薄膜结构湿模态概念,考虑外流场对薄膜充气梁的耦合作用,分别采用拟密度法和流固耦合法计算了薄膜充气梁的湿模态,通过与干模态的比较验证了外流场对薄膜充气梁的耦合效应。 相似文献
415.
416.
Ludovic Dume′ e Aaron Thornton Kallista Sears Ju¨ rg Schu¨ tz Niall Finn Steven Spoljari Robert Shanks Chris Skourtis Mikel Duke Stephen Gray 《自然科学进展(英文版)》2012,22(6):673-683
In-situ thermal expansion tests on a series of carbon nanotube bucky-paper composites
were performed with direct heating within a synchrotron SAXS source. The impact of the samples
density and morphology as well as the chemistry and degree of decoration of the carbon nanotubes
on the scattering patterns were investigated and correlated to the materials macro-properties. The
results demonstrate that simple densification techniques, such as acetone dipping or gold electroless
deposition, could reduce greatly the displacements of the carbon nanotubes within the structure
and lead to more thermally stable material. 相似文献
417.
A PGC1-α-dependent myokine that drives brown-fat-like development of white fat and thermogenesis 总被引:1,自引:0,他引:1
Boström P Wu J Jedrychowski MP Korde A Ye L Lo JC Rasbach KA Boström EA Choi JH Long JZ Kajimura S Zingaretti MC Vind BF Tu H Cinti S Højlund K Gygi SP Spiegelman BM 《Nature》2012,481(7382):463-468
418.
419.
Lounkine E Keiser MJ Whitebread S Mikhailov D Hamon J Jenkins JL Lavan P Weber E Doak AK Côté S Shoichet BK Urban L 《Nature》2012,486(7403):361-367
Discovering the unintended 'off-targets' that predict adverse drug reactions is daunting by empirical methods alone. Drugs can act on several protein targets, some of which can be unrelated by conventional molecular metrics, and hundreds of proteins have been implicated in side effects. Here we use a computational strategy to predict the activity of 656 marketed drugs on 73 unintended 'side-effect' targets. Approximately half of the predictions were confirmed, either from proprietary databases unknown to the method or by new experimental assays. Affinities for these new off-targets ranged from 1 nM to 30 μM. To explore relevance, we developed an association metric to prioritize those new off-targets that explained side effects better than any known target of a given drug, creating a drug-target-adverse drug reaction network. Among these new associations was the prediction that the abdominal pain side effect of the synthetic oestrogen chlorotrianisene was mediated through its newly discovered inhibition of the enzyme cyclooxygenase-1. The clinical relevance of this inhibition was borne out in whole human blood platelet aggregation assays. This approach may have wide application to de-risking toxicological liabilities in drug discovery. 相似文献
420.
H Pälike MW Lyle H Nishi I Raffi A Ridgwell K Gamage A Klaus G Acton L Anderson J Backman J Baldauf C Beltran SM Bohaty P Bown W Busch JE Channell CO Chun M Delaney P Dewangan T Dunkley Jones KM Edgar H Evans P Fitch GL Foster N Gussone H Hasegawa EC Hathorne H Hayashi JO Herrle A Holbourn S Hovan K Hyeong K Iijima T Ito S Kamikuri K Kimoto J Kuroda L Leon-Rodriguez A Malinverno TC Moore BH Murphy DP Murphy H Nakamura K Ogane C Ohneiser C Richter R Robinson EJ Rohling O Romero K Sawada H Scher 《Nature》2012,488(7413):609-614
Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carbon input from volcanic and metamorphic outgassing and its removal by weathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The integrated effect of these processes is reflected in the calcium carbonate compensation depth, which is the oceanic depth at which calcium carbonate is dissolved. Here we present a carbonate accumulation record that covers the past 53 million years from a depth transect in the equatorial Pacific Ocean. The carbonate compensation depth tracks long-term ocean cooling, deepening from 3.0-3.5?kilometres during the early Cenozoic (approximately 55?million years ago) to 4.6 kilometres at present, consistent with an overall Cenozoic increase in weathering. We find large superimposed fluctuations in carbonate compensation depth during the middle and late Eocene. Using Earth system models, we identify changes in weathering and the mode of organic-carbon delivery as two key processes to explain these large-scale Eocene fluctuations of the carbonate compensation depth. 相似文献